Navegando por Palavras-chave "Comet Assay"

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    Avaliação da expressão tecidual do gene de reparo MLH1 e dos níveis de dano oxidativo ao DNA em doentes com câncer colorretal
    (Cidade Editora Científica Ltda, 2009-09-01) Martinez, Carlos Augusto Real; Cordeiro, Adriana Teixeira; Priolli, Denise Gonçalves; Miranda, Daniel Duarte Da Conceição; Bartchewsky Júnior, Waldemar [UNIFESP]; Margarido, Nelson Fontana [UNIFESP]; Ribeiro, Marcelo Lima; Universidade São Francisco; Universidade São Francisco Hospital Universitário São Francisco Serviço de Cirurgia Geral; Universidade Federal de São Paulo (UNIFESP)
    The oxidative DNA damage caused by oxygen free radicals is one of the most important mechanisms responsible for the initial steps of colorectal carcinogenesis. The oxidative stress can cause errors in the pairing of nitrogenous bases that form the DNA, allowing mutations in controlling genes of the cell cycle. The cells have a defense system represented by the DNA mismatch repair genes that correct the errors of matching prevent the development of DNA mutations. Few studies have evaluated the relationship between oxidative DNA damage and the tissue expression of mismatch repair genes. AIM: The aim of the present study was evaluate the levels of oxidative DNA and the tissue expression of MLH1 mismatch repair gene in the cells of normal and neoplastic colonic mucosa of patients with colorectal cancer. MATERIAL AND METHODS: Were studied 44 patients with diagnosis of colorectal adenocarcinoma. Were excluded patients with hereditary colorectal cancer, with colorectal cancer associate with inflammatory bowel diseases and those undergoing neoadjuvant radioquimiotherapy. To evaluate the levels of oxidative DNA damage was used the single cell gel electrophoresis (comet assay) evaluating 100 cells obtained from normal and neoplastic tissues. For the evaluation of the tissue expression of MLH1 gene was employed the technique of polymerase chain reaction in real time (RT-PCR) with primer specifically designed for MLH1 gene. The comparison among the levels of DNA oxidative stress and expression of MLH1 mismatch repair gene in normal and neoplastic tissues was done by Student t test adopting a significance level of 5% (p< 0.05). RESULTS: The levels of oxidative DNA damage in tumor tissue were significantly higher when compared to the level of the normal tissue (p = 0.0001). The tissue expression of MLH1 mismatch repair gene in tumor tissue was significantly lower when compared to normal tissue (p=0.02). CONCLUSION: The mismatch repair gene MLH1 are less expressed in tumor tissue and inversely related to levels of oxidative DNA damage.
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    The influence of sleep deprivation and obesity on DNA damage in female Zucker rats
    (Faculdade de Medicina / USP, 2013-01-01) Tenório, Neuli Maria [UNIFESP]; Ribeiro, Daniel Araki [UNIFESP]; Alvarenga, Tathiana Aparecida [UNIFESP]; Fracalossi, Ana Carolina Cuzzuol [UNIFESP]; Carlin, Viviane [UNIFESP]; Hirotsu, Camila [UNIFESP]; Tufik, Sergio [UNIFESP]; Andersen, Monica Levy [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    OBJECTIVE: The aim of this study was to evaluate overall genetic damage induced by total sleep deprivation in obese, female Zucker rats of differing ages. METHOD: Lean and obese Zucker rats at 3, 6, and 15 months old were randomly distributed into two groups for each age group: home-cage control and sleep-deprived (N = 5/group). The sleep-deprived groups were deprived sleep by gentle handling for 6 hours, whereas the home-cage control group was allowed to remain undisturbed in their home-cage. At the end of the sleep deprivation period, or after an equivalent amount of time for the home-cage control groups, the rats were brought to an adjacent room and decapitated. The blood, brain, and liver tissue were collected and stored individually to evaluate DNA damage. RESULTS: Significant genetic damage was observed only in 15-month-old rats. Genetic damage was present in the liver cells from sleep-deprived obese rats compared with lean rats in the same condition. Sleep deprivation was associated with genetic damage in brain cells regardless of obesity status. DNA damage was observed in the peripheral blood cells regardless of sleep condition or obesity status. CONCLUSION: Taken together, these results suggest that obesity was associated with genetic damage in liver cells, whereas sleep deprivation was associated with DNA damage in brain cells. These results also indicate that there is no synergistic effect of these noxious conditions on the overall level of genetic damage. In addition, the level of DNA damage was significantly higher in 15-month-old rats compared to younger rats.